Short-circuiting device



Nov. 4 1924. 1,513,799

H. L. BRUMP SHORT CIRCUITING DEVICE Filed July 26, 1923 INVENTOR,

20 A TTORNEY.

Patented Nov. 4, 1924.

'UNITED STATES PATENT OFFICE.

HERBERT L. BRUMP, OF DAYTON, 0810, ASSIGNOR TO THE DAYTON FAN & MOTOR COMPANY, A CORPORATION OF OHIO.

SHORT-CIRCUITING DEVICE.

Application filled July 26, 1923. Serial No. 653,917.

To all whom it may concern:

Be it known that I, I'IERBERT L. BRUMP, a. citizen of the United States, residilplg in the city of Dayton, in the county of outgomery and State of Ohio, have invented certain new and useful Improvements in 'Short-Circuiting Devices, of which the following is a specification.

This invention relates primarily, though not exclusively, to certain alternating current motors known to the trade as repulsion induction motors, and is an improvement upon the short-circuiting device therefor illustrated and described in my United States Letters Patent No. 1,458,682 granted June 12th, 1923.

It is the principal object of my invention to provide a spacer for the centrifugal weights to prevent them from grouping together at one side of the commutator and without interfering with their natural movemrnt. The spacer is free to revolve around the shaft, the weights deriving their driving force from frictional contact with the latter.

It is another object of my invention to bevel the spring engaging surfaces of the centrifugal weights so that they will incline toward the copper disc, thereby the better to maintain the spring in contact with the latter. When the motor slows down the spring will make a clean break with the commutator, which is not always the case when the weights are not beveled, since there is then a tendency for the spring to drag against the commutator, forming. an electric are.

In the accompanying drawings illustrating my invention, Figure 1 is a side elevation, partly in section, of the device, showing the u per weights in. a running position and the lower ones in a starting position. Fi re 2 is an end elevation of the device, wlth the shell partly broken away to show the spring, the weights and the spacer for the latter. Figure 3 is a plan view of the s acer for the weights. Figure 4 is a si e view thereof. Figure 5 is a sectional view taken through the spacer to show one of its guiding ears. Figure 6 is a front view of one of the beveled weights. And Figure 7 is a side view thereof.

Throughout th specification and drawings, similar reference characters denote corresponding parts.

In a detailed description of the forms of embodiment of my invention illustrated in the accompanying drawings, the numeral 1 designates an armature shaft upon which is mounted a commutator spider 2. Secured to the latter in the conventional manner is a circumferential series of commutator bars 3 of uniform length. (See Figure 1.)

Secured on the shaft 1 a short distance in front of the commutator just described, is the hub 4 of a copper disc 5, the former being preferably constructed of steel and having a reduced inner end that is pressed in a central hole in the disc to turn the latter when the armature shaft is rotated. (See Figure l.)

The inner surface of the disc 5 is but a short distance removed at its outer end from the inwardly tapering end portions of the commutator bars 3, to permit a coil spring 6, preferably constructed of phosphor bronze, to make contact with boththe disc and the commutator bars forthe purpose of short circuiting the latter when the spring is expanded by the centrifugal means now to be described.

Mounted loosely on the armature'shaft 1 behind the copper disc 5, is a spacer disc 7 that is preferably constructed of light metal as a stamping. Turned outwardly at right angles from the outer faceof the spacer disc 7 is a series of equally-spaced guiding ears 8 between each two of which a segmental weight 9, preferably constructed of steel, is free to move outwardly when the armature shaft is rotated. The ears 8 on the spacer disc keep the weights 9 from grouping together at one side of the commutator, but in no wise interfere with the natural movement of them.

The outer periphery of each one of the segmental weights 9 is beveled so as to slope toward the copper disc 5. Surrounding the beveled peripheries of these weights, the coil spring; 6 is normally held by them in contact with the inner surface of the copper disc, and out of contact with the inwardly tapering end portions of the commutator bars 3 when the armature shaft 1 is at rest. (See the lower portion of Figure 1.)

W hen rotation of the armature shaft is started, these weights 9, being free to slide outwardly between the ears, 8 of the spacer 7, will act as centrifugal elements to press spring 6 outwardly as the speed gagement with the copper disc 5 b f the armature shaft increases, until it contacts with the tapering end portions of the commutator bars to short circuit them, said spring being at all times maintained in enthe beveled peripheries of the weights. eginning with the time of contact of the spring with the commutator bars, the short circuited armature will functionas the squirrel cage rotor of an induction motor, but up to that time the device will start as a repulsion motor having series characteristics.

When the armature shaft starts to slow down, the weights 9 through their beveled peripheries will have a tendency to draw the spring away from the commutator bars for a clean break with them, thus avoiding the objectionable arcing which is produced when the spring drags against them during the slowing-downmovement.

Iv do not wish to belimited to the details of construction and arrangement herein shown and described, and any changes or modifications may be made therein within the sco of the subjoined claims.

Having described my invention, I claim:

1. In an alternatingirurrent motor, an

armature shaft, a commutator mounted thereon, an annular member also mounted on said shaft opposite the commutator, a series of centrifugal elements, free to move outwardly,'fm ourited between the annular member and commutator, a flexible element adapted to be moved outwardly. by the centrifugal elements, when the armature shaft attains a certain speed, to make ,contact between the annular member and the commu-' member and commutator, a flexible element adapted to be moved outwardly by the centrifugal elements,'when the armature shaft attains a certain speed, to make'contact between the annular member and the commutator for the purpose of short circuiting the latter, a spacer disc loosely mounted on the armature shaft between the commutator and the centrifugal elements, and equally spaced outwardly projecting ears on the spacer disc between which the centrifugal elementsar'e freely movable, for the purpose specified.

3. In an alternating current motor, an armature shaft, a commutator mounted thereon, an annular member also mounted on said shaft opposite the commutator, a series of centrifugal weights which have beveled peripheries that slope toward the annular member, free to move outwardly between the latter and the commutator, and a flexible element surrounding the beveled peripheries of the weights and maintained by them in contact with the annular member, said flexible element adapted to be moved outwardlyaby the weights,when the armature shaft attains a certain speed, to make contact between said annular member and the commutator for the short circuiting the latter.

t 4. In an alternating current motor, an

armature shaft, a commutator mounted thereon, a copper disc also mounted on the armature shaft opposite the commutator, a series of segmental weights that have beveled outer peripheries that slope toward the copper disc,--free to moveoutwardly between the latter and the commutator, and a garter spring surrounding the beveled peripheries of the weights and maintained by them in constant contact with the copper disc, said spring adapted to be moved out" wardly by the weights, when the armature shaft attains a certain speed, to make contact between the copper disc and the commutator for the purpose of short circuiting the latter.

In testimony whereof I have hereunto set my hand this 23rd da of July, 1923.

HER ERT L. BRUMP. Witness:

HowARn S. SMITH.

purpose of 

